1. Field of the Invention
The present invention relates to a lens barrel holding a plurality of lenses, more particularly, relates to the lens barrel holding the lenses movably in forward and backward directions in a photographic optical axis direction.
2. Description of the Related Art
In recent years, in a photographing apparatus such as a digital camera or the like, a small size and high image quality of a photographed image have been required. In order to satisfy the high image quality requirement, it has been proposed to increase a number of lenses used in an optical system. In order to satisfy the small size requirement, a lens barrel having configurations in that each lens is collapsed in a camera body in a non-photographing mode, and extends from the camera body in a photographing mode has been proposed. In order to satisfy the high image quality requirement, a position of each lens with respect to the photographic optical axis viewed in a direction orthogonal to the photographic optical axis is preferably positioned in a predetermined position regardless of the forward and backward positions. Therefore, a frame moving mechanism in which accuracy for supporting lenses can be easily ensured in the lens barrel is proposed (see Japanese Patent Application Publication Number H07-151949).
In the lens barrel (the frame moving mechanism), two projection portions are provided on an inner surface of a fixed frame holding a lens holding frame movably in a photographic optical axis direction and a plate spring is provided on a circumferential wall portion of the fixed frame so as to face the two projection portion across the photographic optical axis. The lens holding frame in the fixed frame is pressed by the plate spring toward the two projections. Therefore, in the lens barrel (the frame moving mechanism), the position of the lens holding frame holding each lens in the fixed frame is positioned in a position so as to come into contact with the two projections regardless of the forward and backward direction.
However, in the above described conventional lens barrel (the frame moving mechanism), although the lens holding frame is movable in forward and backward directions in the photographic optical axis direction in the fixed frame, the lens holding frame is pressed by the plate spring fixedly provided on the fixed frame is pressed and therefore a biased position with respect to the lens holding frame by the plate spring varies in accordance with the position of the lens holding frame in the photographic optical axis direction. Therefore, there is a problem in that the biasing force applied to the lens holding frame and an applied state of the biasing force is not necessarily maintained constant.